In the field of packaging food and non-food liquid and/or flowable food and non-food products, a convenient method of packaging such products in thermoplastic film has been developed and is ggenerally known as a form-fill-seal process. In such a process a tube is formed from thermoplastic film and the bottom end seal is made by transversely sealing across the tube with heated seal bars to form a conveniently wide heat seal and, consequently, producing a bag or pouch ready to receive a product. After the heat seal is made, the bag or pouch is filled and then another transverse heat seal is made across the width of the tube in a relatively wide band. After cooling, this seal is transversely severed to separate the fill bag from the next bag to be filled. Thus, one wide band seal serves as the bottom seal for one bag and the top seal for another.
A machine for making bags in a vertical form-fill-seal machine is described in U.S. Pat. No. 4,506,494 which issued on Mar. 26, 1985 to Mamoru Shimoyama et al. In the Shimoyama patent a vertically held tube with a bottom end that has been closed by a transverse heat seal is filled with a liquid, semiliquid, or paste charge or contents and squeeze rollers spaced apart and above the bottom end seal squeeze the filled tube and pinch the walls of the flattened tube together. When a length of tubing of the desired height of the bag has been fed through the squeeze rollers a heat seal is made transversely across the flattened tubing by heat seal bars which clamp and seal the film of the tube therebetween. After the seal bars have been withdrawn the film moves downwardly to be contacted by cooled clamping and severing bars which clamp the film therebetween and are provided with a cutting knife to sever the sealed film at about the mid point of the seal so that approximately half of the seal will be on the upper part of a tube and the other half on the lower. When the sealing and severing operation is complete, the squeeze rollers are separated to allow a new charge of product to enter the flattened tube after which the aforementioned described process is repeated thus continuously producing vertically form-fill-seal bags which have a bottom end and top end heat seal closure.
One of the drawbacks of such sealed bags is that the heat seal which is of flattened, relatively strong and tough thermoplastic film is made even stronger and tougher by the fact that it is now a two-ply heat welded band which requires a knife or scissors or other cutting device to open the pouch. Accordingly, it is one object of the present invention to provide an apparatus, a bag, and method for making same which produces a manually operable guided tear, easy open seal.
Another object of the present invention is to provide a bag with an easy open feature wherein the easy open feature does not detract or injure the package quality nor affect the contents of the package.
Yet another object of the present invention is to provide a convenient and efficient way of making an easy open bag which can be incorporated into existing form-fill-seal bag making equipment.
These and other objects will be readily apparent to those skilled in the art from the following Summary of the Invention, Description of the Drawings, and Detailed Description.